Halo 2 was a disappointment, Halo 3 and ODST were fun and enough epic moments to pull it back on par with the first. This is of course purely from a campaign standpoint. I guess 4 player Legendary coop campaign this generation was a much more enjoyable experience for me hence the high regard for 3 and ODST.

The original Quake maybe, but there's no way it's better than Quake 2 or 3. 

The combat in HL1 maybe, but everything else was better. HL2 is the best game ever made, in every single aspect.

For not being a ripoff of Ender's Game, it has the EXACT same premise.

Well you can't compare Halo: CE against Quake 3 since Quake 3 is multi-player focused while Halo: Combat Evolved is single-player focused with a great multi-player component. Halo: CE has a stronger single-player than Quake 2, but Quake 2 and 3 have better multi-player. Half-Life 2 is not the best game ever made, there is not the best because that is completely subjective. Halo still has better combat, battles and A.I. than the Half-Life games even though Half-Life 2 is a better game than Halo: CE.

Erm...depends on your definition of "starting from the bottom". If you mean sales...you clearly misread the OP. Now if you think Halo SP got better with each new development...well, that's odd, but hey, to each their own.

You're right, I'm sorry. Half-Life 2 isn't the greatest game ever made, Prince of Persia: The Sands of Time is.

How can you say the A.I. in Halo games is ever decent, it's horrendous!

The combat in the two games is completely different. In Halo, it's more focused on straight up filling the enemy full of lead, where as in HL it's more about using your surroundings and the environment to your advantage. It also features limited weapons and rebounding heatlh, both of which were implemented to dumb-down FPSs for consoles. Personally, I hate the Halo style.

As far as battle go, I've never played a FPS with a bigger and better battle than the end of Episode 2. The rest of the HL series has great battles as well. Fighting off a helicopter with a mounted gun on a speed boat as the helicopter drops wave after wave of bombs on you is better than any battle in the Halo series.

Also, I'd disagree that the SP in Halo is better than Quake 2, I'd say that they are equal (with the Halo story being leaps and bounds better).

Well because i disagree with you. IMO Halo 2 had the best campaign followed by Halo CE. Ind i care alot more about MP than i do single player so it didnt really bother me. But Halo Reach looks sweet!

The enemy A.I. in the Halo games are excellent and your teammates (With the exception of 3 & ODST) were adequate, they actually get smarter at higher difficulty levels. While the A.I. in Half-Life was very good, the enemy and friendly A.I. in Half-Life 2 was pretty poor. The most advanced tactic they've ever used is side step a little during a fire fight. 

The enemy A.I. in the Halo games are smart because of the following:

• They take cover behind something while they're under fire
• Duck behind chest high objects
• Roll out of grenades
• Flank you while you're being suppressed or not paying attention
• Throw grenades at you while you're riding a vehicle are taking cover
• Command nearby vehicles
• Work in groups
• Retreat while outnumbered
• Elites take cover while their shields are down
• They become extremely aggressive once you're outnumbered

The combat in Halo is better because the weapons are better balance and you need to make good uses of the grenades and melee attacks. The vehicles as well. The gunplay in the first Half-Life was excellent but the gunplay felt flat in Half-Life 2 but the Gravity Gun was awesome. Better than any weapon in Halo.

I've seen the enemies do all of those things in Half-Life, much better than they do in Halo (with the exception that enemies don't use vehicles, simply because it's not actually in the game).

Once again, the combat in both games is neither better or worse, just different. You don't use melee in HL because they don't exist. Therefore, it's intentionally left out of the game, and wouldn't be better or worse with it. A Half-Life style of shooter doesn't utilize melee attacks, therefore they are redundant.

As for balancing, the weapons in HL are generally well balanced. It may just not seem like it, because you always have access to the most useful gun for the situation, making the other weapons feel useless.

I'll admit that the vehicle sections in Half-Life could have been better, but the difference is in Halo, there are not any specific sections where you are forced to use vehicles (other than Halo 2's banshee level and the end in the warthog). They just make your life easier. In Half-Life, you are generally forced to use vehicles. This alone makes them irrelevant to compare, as they are, at their very core, different experiences.

In summary, Half-Life and Halo are nearly impossible to compare because they are so vastly different. Where they do have similarities, their similar elements are implemented so vastly different that they become completely dissimilar.

P.S. Sands of Time is still the greatest game ever made.

Buy it when the price drops down to $40 or $20.

Actually, the Marines are smarter than the Covenant in Halo's Easy and Normal difficulty settings. However, in the Heroic and Legendary settings the Marines don't stand a chance.

Let's not argue about this because we're both creating a large ass pyramid for crying out loud. :p